The role of water-to-binder ratio on strength of fly ash geopolymer as sustainable green materials in supporting SDG 13Arie Wardhono, Yogie Risdianto, Krisna D. Handayani, Nur Andajani and David W. LawE3S Web Conf., 640 (2025) 01005DOI: https://doi.org/10.1051/e3sconf/202564001005